Various types of shaft bearings are known in which the rotating shaft is journaled or carried in a generally spherical ball. The ball is in turn secured and housed in a multi-part housing which may include a base having a recess or seat in which one area of the ball is received, and a cap or covering which fits over or around an opposite area of the ball. The two housing members are secured together, to hold the ball between them. The universal alignability, at least over limited range, of the ball with respect to the housing enables the bearing to accommodate misalignment with the shaft.
Although there are many self-aligning shaft bearings of this general type, they have tended to involve relatively complex shapes and hence have been relatively expensive to manufacture. There has been a need for a simpler, less expensive self-aligning shaft bearing, apart from the type having a pressed steel housing which does not have the rigidity or appearance that is often required or desired.
Shaft bearings are typically classified either as a pillow block mounting or flange mounting. In a pillow block, the bearing is mounted to a support structure which is generally parallel to the axis of the rotating shaft, whereas in flange mountings the axis of the shaft extends generally perpendicularly to the surface of the support structure. Either type of mounting may be required to carry thrust loads as well as radial loads.
It can be seen that in a pillow block mounting, the clamping force acts on the ball in a direction perpendicular to the axis of the shaft bore, whereas in a flange-type mounting the clamping force on the ball acts in direction parallel to the axis of the shaft bore. The respective ball orientations differ by 90.degree. in the two common types of mountings. For this reason, heretofore it has been the common practice to design given self-aligning bearings for one or the other, but not both types of mountings.
Because these bearings are widely used, the bearing manufacturer has thus been required to provide a wide range of different types of bearings, some with flange mountings, some for pillow block mountings and still others for special installations. The inventory problem has been further complicated by the need to supply bearings in each type for use with many different shaft diameters, and for various different types of bearing service. For example, for some applications, cast bronze journals are most effective; for others, needle bearings are desirable; in still others, high temperature bearings are needed, and so on. All of this has posed a need for bearings which are adaptable for more universal use, to different types of mountings, shaft sizes, bolt hole configurations, load and bearing service.
It has been an object of this invention to provide a self-aligning shaft bearing of relatively simple, rigid, and economical construction wherein a standardized ball can be used with a variety of mountings, in the pillow block mode, the flange mode, or other special mountings, and which can be clamped in either of two positions, at right angles to each other, without deformation or damage. The standardized ball is cooperable with a plurality of sets of caps and bases for various mountings. The standardized ball is also cooperable with a series of bearing inserts of different internal diameters for use with shafts of different diameters, and of different bearing materials and construction to provide different bearing service.
More specifically, in a preferred embodiment the bearing construction includes a ball which can be used in a pillow block mounting mode, a flange mounting mode, or other mounting. A pair of generally parallel flats are formed onto the ball, on opposite sides of the shaft bore therein. Two cylindrical lands extend transversely around the ball, connecting the opposed flats. The flats prevent rotation of the ball in the housing; and the flats and lands together minimize the width of the unit, as will be seen. The ball may be molded and/or sized with a bead running around the ball, centered on the cylindrical lands and the flats. The lands and flats also provide clearance spacing so that the bead does not engage seats in the base and cap between which the ball is clamped.